Electrolytic shaping and cavity sinking apparatus



Nov. 22, 1966 A. WILLIAMS ETAL 3,287,246

ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS Filed June 11, 1962 Sheets-Sheet 2 1966 L. A. WILLIAMS ETAL 3, 8 5

ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS 7 Sheets-Sheet :5

Filed June 11, 1962 INVENTORS Z ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS '7 Sheets-Sheet 4 Filed June 11, 1962 INVENTIORS:

1966 L. A. WILLIAMS ETAL 3, 87, 46

ELECTROLYTIC'SHAPING AND CAVITY SINKING APPARATUS Filed June 11, 1962 7 Sheets-Sheet 5 INVENTORS: Q 2%" I emad age/$0 5k Q9 Nov. 22, 1966 L. A. WILLIAMS ETAL 3,287,245

ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS 7 Sheets-Sheet 6 Filed June 11, 1962 il. ll||.li|llll.ll l I i I I I l l l l ll INVENTORS I aoml /iijaau d/z' Nov. 22, 1966 L. A. WILLIAMS ETAL 3,287,246

ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS Filed June 11, 1962 7 Sheets-Sheet 7 United States Patent 3,287,246 ELECTROLYTIC SHAPING AND CAVITY SINKING APPARATUS Lynn A. Williams, Winnetka, and Leonard Malkowski,

La Grange, 111., assignors to Anocut Engineering Company, Chicago, 111., a corporation of Illinois Filed June 11, 1962. Ser. No. 201,679 18 Claims. (Cl. 204-224) This invention relates to an electrolytic shaping and cavity sinking apparatus, and particularly to such apparatus wherein the current and the electrolyte are carried through the assembly for relatively moving the workpiece and the electrode toward each other. The invention further relates to an electrolytic lathe.

It has been discovered that contours in the cavities in and through electrically conductive and electrochemically erodable workpieces can be formed by a hollow electrode having electrolyte flowing therethrough under appreciable pressure and with a low potential, high density, direct current passed simultaneously between the electrode and workpiece. This method and the apparatus forpracticing it are described in copending applications of Lynn A. Williams, Serial No. 772,960, filed November 10, 1958, issued into Patent No. 3,058,895, dated October 16, 1962, and Serial No. 73,154, filed September 2, 1960, and with respect to certain details, in other copending applications of Lynn A. Williams.

In the apparatus of these prior applications, and particularly that of application Serial No. 73,154, the electrolyte is fed to land through the interspace between the working face of the electrode and the workpiece under substantial pressure which may be high as 300 pounds per square inch and as low as 30 pounds per square inch. The technique disclosed is to mount a hollow or tubular electrode on a manifold carried at the forward end of a movable ram. The manifold is connected by heavy and large capacity hoses through suitable control valves and filters to a high pressure pump which draws electroylte from a tank. After being pumped through the interspace the electrolyte is returned to the tank for reuse.

The negative output terminal of the power supply is connected to the electrode mount, usually a plate forming a part of the manifold by one or more heavy duty cables. In an installation where the total amperage needed for electrolysis is 10,000 amperes, it has been found necessary to used cables of the welding equipment type, each of 600,000 circular mils capacity. These are fitted with lugs of the hermetically sealed type for connection to the electrode mount. The total weight of the cables and lugs in this installation is 375 pounds, and this weight being at least in part from the electrode mount, exerts undesired torsion on the mount, the manifold, and the ram, which creates a condition having the distinct possibility, if not probability, of causing the electrode not to move on its intended path. Obviously, this results in a shaped workpiece or cavity not conforming to specifications.

It will be appreciated that in the apparatus of application Serial No. 73,154, the hose and cables will hang in the work area and under some conditions become bothersome obstructions. Under most operating conditions, the work area, which is confined, will have a mist of electrolyte therein. The electrolyte has a corrosive action and will attack the cable unless precautions are taken. This attack occurs by the electrolyte entering under the insulating sheath of the cable and working its way inwardly through the interstices of the cable wires by capillary action. The electrolyte remains in the cable and corrodes its copper wires. It has been found that such corrosion may extend inwardly from the end of the cable as much as five feet. To minimize such corrosion, it has been necessary to skive the insulation at the outer end of the cable to lit ice it to a lug of the hermetically sealed type. Such lugs are very costly and not altogether reliable in their sealing.

The present invention provides an apparatus for carrying out the electrolytic method of the previously mentioned application, but completely removes the hoses and cables from the work area. This eliminates the problems of cable corrosion, of placing stresses on the electrode mount, and of obstructions in the work area.

It is a principal object of the present invention to provide an electrolytic shaping or cavity sinking apparatus wherein the electric and electrolyte supply connections are made with the electrode by means other than cables and hoses in the work area.

Another object is to provide an improved electrolytic shaping apparatus wherein the current and electrolyte are carried through the assembly for relatively moving the workpiece and the electrode toward each other, whereby electric cables and electrolyte tubes and hoses are eliminated from the work area.

It is a further object to provide an electrolytic lathe wherein the workpiece is rotated with respect to the electrode for versatile shaping operations.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a partially cut away plan view of the drivehead assembly of an electrolytic shaping or cavity sinking apparatus constructed according to the present invention;

FIG. 2 is a partially cut away sectional view of the drivehead assembly of FIG. 1, taken along the line 2-2 of FIG. 1, looking in the direction of the arrows;

FIG. 3 is a transverse sectional view, taken along the line 33 of FIG. 1, looking in the direction of the arrows;

FIG. 4 is a longitudinal sectional view, taken along the line 44 of FIG. 1, looking in the direction of the arrows;

FIG. 5 is a fragmentary longitudinal sectional view, taken along the line 55 of FIG. 1, looking in the direction of the arrows;

FIG. 6 is a plan view of an electrolytic lathe incorporating the structure of the present invention, including a work holder assembly and a drivehead assembly;

FIG. 7 is a longitudinal sectional view of the drivehead assembly of the electrolytic lathe of FIG. 6, taken along the line 7-7 of FIG. 6, looking in the direction of the arrows;

FIG. 8 is a fragmentary longitudinal sectional view, taken along the line 8-8 of FIG. 6, looking in the direction of the arrows;

FIG. 9 is a transverse sectional view, taken along the line 99 of FIG. 7, looking in the direction of the arrows;

FIG. 10 is a transverse sectional view, taken along the line 1010 of FIG. 7, looking in the direction of the arrows;

FIG. 11 is a longitudinal sectional view of the work holder assembly of the electrolytic lathe, taken along the line l1--11 of FIG. 6, looking in the direction of the arrows;

FIG. 12 is a view similar to FIG. 4, illustrating a further form of the invention with some portions shown schematically; and

FIG. 13 is an enlarged schematic illustration of the relationship between a typical electrode and workpiece, using the equipment of FIG. 12.

Referring to the drawings, and more particularly to FIGS. 1-5, the drivehead assembly of the electrolytic cavity sinking apparatus of the present invention is indicated generally by reference numeral 20, and is adapted to advance a hollow, tubular, or solid electrode 38 smoothly, positively, and precisely toward and into working relationship with a workpiece (not shown) in a work area. The drivehead assembly 20- is mounted upon a base (not shown) and includes an axially movable ram, indicated generally at 26, supported within and projecting from a. housing 25. The housing 25 includes a base 22 and a cover 24. The ram 26 includes a long hollow square member 28, normally a heavy casting (FIG. 4), having secured to opposite ends an end plate 30 and a ram head 32, both being made of steel. An electrically conductive electrode mounting plate 36 supporting the electrode 38 is secured to the ram head 32 in a manner to be described in more detail hereinafter.

A plurality of recirculating roller bearing assemblies 34 mounted within the housing25 cooperate with the ram element 28 to support the ram 26 for axial movement. In each of the two planes one set of bearings is solidly mounted and the opposite set is adjustable to permit preloading. The roller bearings 34v also prevent rotation of the ram 26 by bearing upon the two surfaces adjacent the four corners of the ram.

The ram 26 is driven forward and backward by a lead screw 40 (FIG. 4) which cooperates with a lead nut assembly 42 secured to the end plate 30. The lead nut assembly 42 includes a fixed nut 44 and an adjustable nut 46. The nut 44 is keyed within the assembly 42. A set screw 43 or the like in the assembly 42 cooperates with the nut 46 to hold it in place after it has been properly adjusted.

The lead screw 40 is rotatably supported by roller thrust bearings 48 mounted within the housing 25, and is driven through a sprocket 50 by a chain 52; Through the cooperation of the lead screw 40 with the lead nut assembly 42, rotational motion of the lead screw 40 causes axial movement of the ram 26. An electric brake 54, spring biased to braking position, is mounted between the sprocket 50 and the roller thrust bearings 48 and is operatively connected to. the lead screw 40. It is energized when the apparatus is running to release the brake, but deenergized when the apparatus is stopped so as to arrest rotary motion of the lead screw 40 and thus prevent overtravel of the ram 26 beyond the desired limits.

The power unit for the drive mechanism is mounted upon the cover 24 of the housing 25. and includes a variable speed gear head and motor unit 56 and a rapid traverse motor 58 interconnected by a clutch 60. The cooperation of the variable speed motor unit 56 and the rapid traverse motor 58 in conjunction with suitable control means (not shown) rotates the leadscrew 40 in either direction at variable speeds whereby the ram 26 may be moved forward or backward, rapidly or slowly. Usually, the rapid traverse motor 58 brings the electrode 38 to working position relative to. the workpieces and removes it when the shaping or cavity sinking operation has terminated. The variable speed motor unit 56 moves the electrode into the workpiece at a closely controlled rate during the. actual shaping or cavity sinking operation.

Secured to the ram head 32 by bolts 62 is. an electrically nonconductive plate 64. (FIG. 4) made of nylon, epoxy resin, or the like. A dished or cupped manifold plate 66, to which the electrode mounting plate 36 is attached by means ofbolts 67 or the like, is secured to the plate 64 by bolts 65v or the like. Boththe manifold plate 66 and the electrode mounting plate 36 are made of electrically conductive metal and form an electrolyte manifold. chamber 68 which communicates with the electrode.

38, illustrated as being hollow or tubular. The manifold and its supply system, to be described hereinafter, are so proportioned that a continuous supply of electrolyte is available to be pumped Without appreciable pressure loss through the electrode 38, or a plurality of them, to the work gap between the workpiece and the electrode working faces under the conditions required to be satisfied by adequate electrolytic material removal rates.

Electrolyte is delivered to the electrolyte manifold.

chamber 68 and the electrode 38 by means of one or more pipes 70 which extend through the drivehead assembly 20 and more particularly through the ram 26. The pipe 70 enters the ram 26 through a clearance hole 72 in the end plate 30. Itpasses through aligned clearance holes 73 and 75 of the ram head 32 and the plate 64, respectively, and is threaded into a hole in the manifold plate 66 (FIG. 4). In this manner the pipe 70 communicates with the electrolyte manifold chamber 68. The exterior end of the pipe 70 is held in place by a positioning memi ber 74 and a cooperating clamping member 75 suitably secured to the end plate 30 and defining a hole therebetween adapted firmly to engage the outer periphery of a portion of electrolyte tube 70 to prevent it from con.

tacting the end plate 30. The members 74 and 75 are made of electrically nonconductive material, such as fiberglass or the like, and prevent electrical contact between the pipe 70 and the ram.

A coupling 76 connects the pipe 7 0 with a flexible tube 78 connected in turn to a pipe 81 communicating with a pump (not shown) which delivers electrolyte under relatively high pressures, mg, in the range of 30 to 300 p.s.i.,

as more fully disclosed in copending application Serial It should also be noted that the flexible tube or hose,

78 is made of electrically nonconductive material so that there will be no direct metallic conductive path back to the pump and frame from the electrode mounting.

As the ram 2.6 moves axially hack and forth, electrolyte pipe 70 will move with the ram 276. A longitudinally extending opening 79 in the basemem ber 22 (FIGS. 3 and 4) allows the flexible tube 78 to follow the electrolyte tube 70. The tube 81 flexes during movement of the,

ram 26.

Proper temperature of the electrolyte is maintained by suitable control means, heating elements, and cooling means (not shown). It is preferred that the electrolyte be within the range of about to 180 F., but this may be varied according to the electrolyte employed.

Low potential, high density direct current is applied between the electrode 38 and the workpiece, and the power supply therefor is connected to the electrode 38 i by a plurality of cables 80. Two bus bars 82 extending through the ram 26. and through aligned clearance holes 90, 91, and 93 are connected. by bus .plates 84.:

and 86, to the cables 80 (FIGS. 3 to 5). One end' of each bus bar '82 extending through the aligned clearance holes 91 and. 93 is connected to the manifold plate 66 by means of a bolt 88 (FIG. 5). The other end of each bus bar 82 extends through the clearance holes 90' in the end plate 30. This end of. the. bus bar '82 is supported. by the positioningplate 74 discussed hereinbefore. An additional electrically nonconductive locking plate 92 is posi-v tioned over the end of each b-us bar 82 and secured to the end plate 30 -by suitable means (FIGS. 3 and 5.). The

plates 92 cooperate with the positioning plate 74. to hold the bus 'bar 82 in spaced relationship from the clearance hole 90 in the end plate 30. Accordingly, the end plate 30 may be constructed of electrically conductive metal since it is not in contact with the bus bars 82.

To protect the ram head 32 and its associated parts (from electrolyte splatter from the work area and also to prevent current from being conductedfromthemanifold plate 66 to the housing 25, an annular metal sheet 94 coated with epoxy containing graphite is secured to the conductive plate '66 and supports, in cooperation with the housing 25, a neoprene boot 96. Additional protection to the front of the drivehead assembly 20 may be provided by a sheet 98 of stainless steel coated with epoxy or plastic material which forms a part of the work area enclosure and is secured between the boot 96 and the housing 25 (FIGS. 1 and 4).

When the ram 26 is moved forward or backward by the variable speed motor 56 or the rapid traverse motor 58, the electric cables 80 and the flexible tubing 73 will follow the movements of the ram 26. It will further be understood that the present construction allows the electrolyte and low potential, high density direct current (4 to 24 volts, up to 8,000 amperes per square inch) to be supplied through the ram 26 and electrode 38 from a source outside the work area in which the electrolytic cutting action is being effected by the elect-rode 38. It will further be noted that the bus bars 82 are insulated from all the electrically conductive parts of the ram 26, with the exception of the conductive plate 66 and the electrode mounting plate 36, and thus the drivehead assembly 20 cannot be electrically energized. In this manner workmen around the drivehead assembly 20 are not subject to electrical shock by contact with the drivehead assembly 20.

The foregoing description assumes that an electrically negative connection is to be made through the bus bars 82 to the electrode mounting plate '36 and thus to the electrode 38, and that the entirety of the frame of the machine ritself, as well as the ram housing 25 and the ram 26, are connected to the positive terminal of the power supply with the positive side being grounded. In the alternative arrangement shown in FIGS. 12 and 13 (which is structurally similar to that of FIGS. 1 to 5, and where feasible the same reference characters are used to designate the same or similar elements) the entirety of the machine frame, including the ram housing 25 and the ram 26, are connected to the negative terminal and grounded. In this case, there is no need for the electrically nonconducti-ve plate 64, and accordingly the manifold plate '66 is secured directly to the ram head 32, using a ground joint to assure good electrical contact. Similarly, there is no need to give special attention to the insulation of the bus bars 82 which extend through the ram 26. Moreover, inasmuch as the ram 26 has extremely heavy sections (in a typical design, the ram is approximately 16" square and has a weight in excess of 3,000 pounds), the basic ram casting 28 may itself be used for conducting current, and thus the flexible cables 80 may be connected directly to the end plate 30 of the ram, and if desired, the bus bars 82 may be reduced in number or size. The end plate 30 is, of course, not insulated and the insulating plate 74 may be eliminated. It is desirable to provide a very ample cross sectional area for conducting heavy currents through the ram in order that resistance heating may be 'held to a In some cases it will be desirable to connect a compressed air line 300 by means of a fitting 302 to the interior of the ram casting 28 so as to feed a draft of cooling air into the hollow midportion of the ram. A vent opening 304 is provided at the back of the ram 26 in the plate 30 to allow the escape of air without the buildup of pressure sufficient to cause bulging of the collapsible neoprene boot 36.

The electrolyte pipe is threaded into the tapped hole in the manifold plate 66 and extends through the opening 304 in the ram plate 30. A U-shaped strap 306, bolted to the plate 30, secures the rear end of the pipe and prevents it from twisting or humping as the ram 26 moves back and forth.

When the electrical connections are made in the manner described immediately above, and as shown in FIG. 12, which is to be regarded as the preferred embodiment of the invention, then the workpiece W is mounted upon a fixture which is, in turn, set upon a plate of insulating material such as laminated, epoxy bonded glass cloth, and the positive connections are taken directly from the power 6 supply to the fixture, which is then arranged to feed the workpiece or workpieces which the fixture holds.

Under these conditions all of the machine frame, the work enclosure, the plumbing,'the electrolyte tank (not shown), pump (not shown), filters (not shown), are all grounded at 308 on the negative side so that they are cathodic with respect to any electrolyte which comes in contact with their surfaces. Thus, there is no risk of undesired anodic attack upon any parts of the machine, as the only metallic parts which are anodic are in or around the workpiece itself, and in practice, the work holding fixture is arranged so that all the clamping and positioning of the workpiece is done with insulating pads or locating elements, and the electrical connection is then made by clamping a bus bar with a suitably resilient surface (copper braid is a preferred material), so that only the workpiece itself, the movable clamping bus bar, and the cables leading to it, are anodic. In this way nothing in or about the work fixture becomes subject to either slow or rapid anodic erosion.

In the schematic illustrations of FIGS. 12 and 13, the workpiece W is shown clamped against an insulating pad 310 by a clamp 3 12. The pad 310 may be epoxy bonded glas fiber laminate and it is mounted on a work table 314 which is adjustable vertically and laterally with respect to the drivehead assembly in the conventional manner. The positive connection to the workpiece is made from electrical cable 315 through a terminal con nection 316 which has the previously mentioned copper braid pad (not shown) against the workpiece. The terminal connection 316 is also mounted on a block 318 of epoxy bonded glass fiber laminate, and it is moved into clamping contact with the workpiece by the means of lever 320 which operates an eccentric or cam.

In this illustration, the electrode 322 is solid, and so the electrolyte cannot be fed through it as was the case with the tubular electrode 38. The electrode 322 is mounted on the mounting plate 36 and is connected to the negative terminal of the power supply through the plate 36, manifold plate 66, the ram head 32, the ram 26, bus bars 82, if used, ram plate 30, connectors 84, 86, and cables 80. The electrode 322, as shown, projects outwardly from the plate 36 and into an electrode guide and electrolyte feed bushing 324 made of an epoxy resin or an epoxy bonded glass fiber laminate which is clamped against the entry surface of the workpiece by the clamp 326. Preferably, the side surfaces of the electrode are coated with an insulation such as a thin layer of epoxy resin, leaving exposed only the working face of the electrode at its tip. The electrode enters the bushing 324 through a snugly fitting opening 328, and electrolyte is fed to the bushing through a hose 330 connected between the mounting plate 36, and therefore the manifold, and

the bushing 324. The hose is of a size sufficient to prevent any appreciable loss of electrolyte pressure. After the electrolyte has passed through the work gap between the electrode working face and the workpiece W it exits through a hole or passage 332 to the work area to drain to the electrolyte tank. If desired, the exit hole or passage 332 may be partially restricted to place a back pressure on the electrolyte in the work gap, thereby improving the smoothness of the finish of the cavity or surface being formed in the workpiece.

The electrolytic lathe of the present invention is illustrated in FIGS. 6 to 11. It includes a work holder assembly and a drivehead assembly 102. The work holder assembly 100 is adapted to rotate the workpiece in the work area. The drivehead assembly 102 controls the axial movement of an electrode 124 as it performs an electrolytic shaping or cavity sinking operation upon the workpiece. The work area is enclosed by a suitable housing 108 of stainless steel, as more fully described in the copending application of Lynn A. Williams, Serial No. 73,154.

The drivehead assembly 102 is mounted on a base 104 and includes an axially movable ram assembly 106 which projects into the work area and the housing 108. The drivehead assembly 102 is, for the most part, enclosed within a housing 109 made of sheet metal.

Mounted within the housing 109, and suitably secured to the base 104, is a stationary guide block 110 which assists in supporting the ram 106 and in guiding the axial movement thereof. The ram 106 includes two hardened steel ram shafts 111 connected to a ram head 112 by bolts 114 (FIG. 7). An electrically nonconductive plate 116 is secured by suitable means (not shown) to the ram head 112 and has secured thereto a manifold plate 118 made of electrically conductive metal. Attached to the manifold plate 118 is an electrode mounting plate 120 which, with the manifold plate 118, forms an electrolyte manifold chamber 122.

An electrode 124, which. in the embodiment shown is a tubular electrode, but it is to be understood that it may be solid, is secured to the electrode mounting plate 120 and communicates with the electrolyte manifold chamber 122. Bosses 121 on the manifold plate 118 contact the electrode mounting plate 120 (FIG. 7) to maintain the desired spaced relationship between the electrode mountiug plate 120 and the manifold plate 118.

The shafts or push rods 111 extend through longitudinal bores 126 in the guide block 110 (FIG. 9). Preferably, anti-friction bearings are used at these points. The push rods 111 are interconnected at their outer ends by a yoke 128 which cooperates with a lead screw 130 by which the ram 106 is driven. The yoke 128 supports two lead nuts 132 and 134. The nut 132 is fixedly secured to the yoke by bolts 133 (FIG. 7), and the nut 134 is adjustable and may be rotated to a limited degree, but is locked to the yoke 128 by bolts 135 during operation of the electrolytic lathe (FIG. 9). The lead screw 130 cooperates with the nuts 132 and 134, whereby rotation of the lead screw 130 causes the yoke 128 to move forward or backward, this movement being transmitted through the shafts 111 to move the ram 106 forward and backward.

The lead screw 130 is supported at its forward end by the guide block 110 and at its rearward end by a support member 142 secured to the base 104. The forward end of the lead screw 130 is mounted in preloaded ballbearings 138, and ball or roller bearings 140 are provided in the support member 142, so that the lead screw 130 is freely rotatable but axially lfixed.

An electric brake 136, spring biased to braking position, is operatively connected to the lead screw 130. The brake 136 is energized when running to release the brake, but deenergized when stopped, so as to arrest rotary motion of the lead screw 130 and thus prevent overtravel of the ram 106 beyond the desired limits. Sprocket-s 144 and 146 are mounted on the lead screw 130 and are operatively connected to a drive mechanism of the type illustrated in FIG. 6.

The drive mechanism includes a motor with a variable speed transmission 148 which is connected to a gear reducer 150 and an electric clutch 152. Through this mechanism a driven chain 154 engages the sprocket 144 to provide forward and backward movement of the ram 106 at predetermined closely controlled rates when the electrode 124 is moving through its forming or cavity sinking ranges. An adjustable chain tension controller 155 is provided to act upon the chain 154 to assure that the rotation force from the motor 148 is being properly transmitted to the sprocket 144.

A rapid traverse motor 156 is connected to the sprocket 146 by chain 158. It is intended that the rapid traverse motor 156 be used to move the ram 106 rapidly, forward or backward, in moving the electrode to or from the working position. The various controls for the motors 148 and 156 have not been illustrated and do not constitute part of the present invention.

The low potential, high density direct current and the electrolyte are supplied to the electrode 124 by means i of bus rods 160 and electrolyte pipes 162, respectively. Each bus rod 160 extends through a longitudinal bore 161 in the guide block and aligned apertures in the ram head 112 and the plate 116, and are secured by a bolt 119, or the like, to the manifold plate 118 (FIG. 8). Insulating bushings 164 of nylon or the like, mounted in the guide block 110, prevent, the bus rods from contacting the guide block 110.

The inner ends of the bus rods 160 are connected to bus bars 165 or 167, which in turn are connected to electric cables 166 (FIG. 9). The electric cables 166 are secured to a terminal 168 mounted on the housing 109 (FIGS. 6 and 9), and which is connected to the source of low voltage, high amperage, direct current of great output capacity. In this manner the current may pass through the bus rods 160 and plates 118 and 120 to the electrode 124.

The electrolyte tubes 162 extend through longitudinal passageways 163 in the guide block 110 and aligned holes in the ram head 112 and the plate 116, and are secured in threaded holes in the manifold plate 118.

into the electrolyte manifold chamber 122. A bushing 164 is also provided at one end of the guide block 110, as seen in FIG. 7 to hold each electrolyte pipe 162, re-

plate 172. The pipes 162 are connected to a manifold 170 which extends through a longitudinal opening 178 r in the base 104 (FIGS. 6, 7, and 9). An electrically nonconductive flange 179 is secured to the manifold 170 below the opening 178 to prevent electrolyte, if it should leak from the pipe section 180, from entering the housing 109. Electrolyte from a suitable high pressure source is pumped through a hose 182 into the manifold 170 through the pipes 162 and into the manifold chamber 122, and thereafter into and through the electrode 124 to and through the work gap, under appreciable superatmospheric pressure.

A portion of the electrolyte pipe 162 is an electrically nonconductive tubular section made of nylon, epoxy resin, or the like. This electrically nonconductive portion is held in fluid sealed relationship with the remainder of the pipe 162 by a clamp and tie rod arrangement, in,-

dicated generally at 176 (FIG. 7).

There is some tendency, while the electrolytic lathe in operating, for current to flow from the electrolyte manifold chamber 122 back through the electrolyte in the electrolyte pipes 162. Likewise, since the pipes 162 J electrically connect with the manifold plate 118, they too will carry current. The nonconductive bushings 164, of course, prevent any current from flowing from. Also, the nonconductive section of the pipe 162 assures that any cur-.

the pipes 162 to the guide member 110.

rent carried by the manifold 170 must be derived from the current in the electrolyte and not from any current carried by the part of the pipe 162 connected to the mam-- fold plate 118. Should electrolyte carry current past this nonconductive section, the bushings 174 prevent any flow of current to the clamping plate 172 and to the driving assembly.

The pipe section 180 (FIG. 9) is employed to prevent unnecessary corrosion in the system, and is a sacrificial pipe section connecting the manifold 170 with the feed hose 182. :rosion and is grounded at 184. Thus, if any current does fiow via the electrolyte through the manifold 170, the section 180 will be corroded, rather than the entire In this manner the electrolyte tubes 162 carry the electrolyte An electrically nonconductive bushing 174 1 It is lined with graphite to reduce cor' piping system. In this manner the destructive effects of any current back flow will be localized in the sacrificial pipe section 180 which may be easily replaced as conditions require.

Referring now to FIGS. 6 and 11, the work holder assembly 100 will be described in more detail. Basically, the work holder assembly 100 is adapted to hold the workpiece (not shown) and rotate it with respect to the electrode 124. The work holder assembly 100 also assures that the workpiece has a positive potential relative to the electrode 124.

To these ends, the work holder assembly 100 includes a work holder 200 mounted upon the forward end of a spindle 202 with a copper core which is rotatably mounted within a guide block 208 in ball bearings 206. The guide block 208 is mounted upon a platform 210 attached to the base 104. The spindle 202 carries a collector ring or commutator sleeve 211 in contact with long brushes 212 which are carried by mounting and terminal bars 214. The latter are bolted to a positive bus plate 216, which in turn is connected to a terminal 217, the latter being connected to the positive output terminal of the power supply and insulated at 219 from housing 226.

The workpiece is secured to the work holder 200 by means not shown in the drawings. If desired, though not necessary, the guide housing 208 may be grounded or, as shown in FIG. 11, insulated from the base or support bracket 210 by a sheet of electrically nonconduotive material 218.

The spindle 202 and the work holder 200 are driven through a pulley 220 mounted on the spindle 202. The pulley 220 is driven by a belt 222 which is, in turn, driven by a pulley 223 on a motor 224. By changing the pulley 223 on the motor 224, various rotational speeds may be imparted to the spindle 202 and the workpiece 200, thereby rotating the workpiece at desired rotational speeds. Ordinarily a speed of about 100 to 200 r.p.m. is used. As seen in FIG. 11, a housing 226 encloses the entire work holder assembly 100. Secured to the work holder 200, and rotating therewith, is an annular member 241 having an outwardly projecting annular bafi-le 242. A stationary seal 228 mounted on the housing 226 cooperates with the rotating member 241. A drip feed oiler 230 lubricates the contacting surfaces of the seal 22S and the member 241.

The housing 108 encloses the work area. Annular baflles 244 extending from the housing 108 cooperate with the bafile 242 and seal 228 to prevent electrolyte splatter from entering the housing 226 from the work area. It will be understood that the housing 108 remains stationary as the baflle 242 and work holder 200 rotate.

During operation of the electrolytic lathe, the workpiece is secured to the work holder 200 and the work holder rotated by means of the motor 224. While the workpiece is rotating, the ram 106 is actuated through the motor 156 to bring the electrode 124 rapidly into working position, and by the motor 148 to move the electrode through the shaping or cavity sinking operation. Once the electrode 124 is ready to enter the workpiece, the speed at which it travels is reduced and usually maintained at a constant rate. The current and electrolyte through the electrode 124 effect the cavity sinking method upon the workpiece, as understood from the previously mentioned applications. It will be understood that with this arrangement annular grooves or the like may be cut in the workpieces. Likewise, if the electrode has a right angle bend, side surfacing or shaping of the workpieces may be effected by the electrolytic lathe.

Furthermore, it will be understood that the drive head assembly 102 may be used in an ordinary cavity sinking arrangement and the drivehead assembly 20 may be used in an electrolytic lathe.

Other modifications may be made. For example, an

electrode useful in electrolytic turning will comprise a circular plate made of plastic with an insert copper sector embracing perhaps 15 to 30 degrees of arc. The copper sector will have in it the contour which is wanted in the workpiece. On one or both sides of the pieshaped sector, there will be slots for feeding electrolyte extending back through the plastic in such way that electrolyte will be fed through these slots from the electrolyte manifold. Some of the electrolyte solution will find its way back over the plastic and will escape without doing any useful work. Some of it, however, will flow out across the pie-shaped copper element and provide a suitable fiow of electrolyte to conduct current between the copper element and the workpiece for material removal. It is intended that the term electrode as used in the claims include and embrace a structure of this type as well as the tubular and solid types illustrated.

Under some circumstances, it may be possible to combine the copper bus bars and the electrolyte feed tubes. Heavy section bus bars might have holes drilled through them for the passage of electrolyte, thus providing thick walled copper tubes which serve the dual function of conducting the electric current and the electrolyte to the manifold and the electrode. The cables and hose 81 (FIG. 4) would be connected to said combined bus bar and electrolyte tube at its end remote from the manifold and the electrode. As many of such dual purpose elements as are necessary should be used.

While the embodiments described herein are at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. In an apparatus :for electrolytically shaping an electrically conductive and electrochemically erodable workpiece in a work area, the combination comprising, a drivehead assembly including a ram and an elongated hollow shaping electrode mounted on one end thereof, said electrode extending into the work area, said ram being supported and guided at axially spaced positions for axial movement thereof, means connected to the second end of said ram for moving said ram toward and away from the workpiece, said ram including means at said first end thereof forming a hollow manifold chamber, means including conduit means extending through said ram to supply electrolyte under pressure to said chamber from said second end of said ram, means to conduct electrolyte under pressure from said chamber to the work gap between said electrode and the workpiece, and means including bus bar means extending through said ram to supply high density, direct current to said electrode from said second end of said ram, electrolyte supply hose connected to said conduit means adjacent said second end of said ram, and a plurality of high current capacity cables connected to said bus bar means adjacent said second end of said ra-m, whereby the work area is free of electrolyte supply hoses and current supply cables for said electrode.

2. In an apparatus for electrolytically shaping an electrically conductive and electrochemically erodable workpiece in a work area, the combination comprising, a drivehead assembly including an elongated hollow ram, means forming an electrolyte manifold chamber carried by said ram at the forward end thereof, said manifold chamber forming means including an electrode mounting plate, a shaping electrode mounted on said plate and extending into the work area, said ram being supported at axially spaced positions for axial movement thereof, means connected to said ram at a second end thereof for moving said ram and said electrode toward and away from the workpiece in the work area, said elect-rode and the workpiece defining a work gap t-herebetween when said electrode is in an advanced position close to the work- .piece, means to conduct electrolyte from said manifold chamber to the work gap between said electrode and the workpiece, means including conduit means extending through said ram to conduct electrolyte under pressure to said manifold chamber from said second end of said ram, means including bus bar means extending through said ram and including said ram for conducting high density, direct current from said second end of said ram to said electrode, electrolyte supply hose connected to said conduit means adjacent said second end of said ram, and a plurality of high current capacity cables connected to said bus bar means adjacent said second end of said ram, whereby the work area is free of electrolyte supply hoses and current supply cables for said electrode.

3. In an apparatus for electrolytically shaping an electrically conductive and electrochemically erodable workpiece, the combination comprising, a machine frame and housing, means in said frame and housing defining a Work area and an electrode drive area adjacent each other, mean-s in said work area for mounting a workpiece including means insulating the workpiece from said machine frame and housing, means connecting the workpiece into an electrolyzing current supply circuit on the positive side thereof, a drivehead assembly in said electrode drive area including an elongated hollow ram, means forming an electrolyte manifold chamber carried by said ram at the forward end thereof, said manifold chamber form ing means including an electrode mounting plate, a shaping electrode mounted on said plate and extending into said work area, said ram being supported and guided at axially spaced positions for axial movement thereof, means connected to said ram at the rear end thereof for moving said ram and said electrode toward and away from the workpiece, said electrode and the workpiece defining a work gap therebetween when said electrode is in an advanced position close to the workpiece, means to conduct electrolyte from said manifold chamber to the work gap between said electrode and the workpiece, means including conduit means extending through said ram to conduct electrolyte under pressure to said man-ifo'ld chamber from the rear end of said ram, bus bar means extending through said ram and connected to said chamber forming means, means connecting said machine frame and housing, said ram, said bus bar means, said manifold chamber forming means, said electrode mounting plate and said electrode into said electrol-yzing circuit on the negative side thereof, electrolyte supply hose connected to said conduit means adjacent said rear end of said ram, and a plurality of high current capacity supply cables connected to said bus bar means and said ram at said rear end of said ram, whereby a direct current is supplied to said electrode and said work area is free of electrolyte supply hoses and current supply cables for said electrode.

4. The apparatus of claim 1, including an end plate mounted on said second end of said ram, and openings through said end plate through which said conduit means and said bus bar means extend.

5. The apparatus of claim 4, wherein one end of said bus bar means and said electrolyte conduit means are supported in spaced relationship to said end plate.

6. The apparatus of claim 5, wherein said ends of said bus bar means and electrolyte conduit means are supported by electrically nonconductive means secured to said end plate.

7. The apparatus of claim 4, wherein said means for moving said ram toward and away from said workpiece includes a lead screw which cooperates with a lead nut assembly secured to said end plate.

8. In an apparatus for electrolytically shaping an electrically conductive and electrochemically erodable workpiece in a work area, the combination comprising, a drivehead assembly including a housing, a ram mounted within said housing for axial movement, said ram having a first end projecting from said housing into the work area and a second end which is maintained in said housing during axial movement of said ram back and forth in the work area, said ram including an elongated annular member having mounted on one end thereof an electrolyte manifold chamber and an electrode which communicates with said electrolyte manifold chamber and forms said first end of said ram, longitudinally spaced guiding and supporting means for supporting said annular member for axial movement, an end plate mounted on the other end of said annular member to form said second end of said ram, separate bus bar and conduit means extending through said annular member from said second end of said ram to said electrolyte manifold chamber and said electrode, multiple high current capacity cable means for supplying high amperage, direct. current connected to said bus bar means at the second end of said annular member, electrolyte supply hose means for supplying electrolyte under pressure connected to said conduit means at the second end of said 1 drivehead assembly including a housing, a ram mounted within said housing for axial movement, said ram having a first end projecting from said housing into the work area and a second end which is maintained in said housing during axial movement of said ram back and forth in the work area, said ram including an elongated annu-' lar member having mounted on one end thereof an electrolyte manifold chamber and an electrode which coma municates with said electrolyte manifold chamber and forms said first end of said ram, an end plate mounted on the other end of said annular member to form said second end of said ram, a bus rod extending through said annular member and said end plate, one end of said bus rod being electrically connected to said electrode and electrolyte chamber at saidrfirst end of said ram, multiple high current capacity cable means for supplyimg high amperage, direct current connected to said bus rod at said other end of said annular member, an electrolyte tube extending through said annular member and said end plate and having an end thereof communicating with said electrolyte manifold chamber, electrolyte supply hose means for supplying electrolyte connected to said tube at said other end of said annular member, whereby electrolyte flows to said electrolyte manifold chamber and said electrode and the work area is free of electrolyte supply hoses and current supply cables, and drive means connected to said second end of said ram to move said ram back and forth within said housing.

Ill/The apparatus of claim 10, wherein said bus rod and electrolyte tube are mounted in spaced relationship from said annular member and said end plate by supporting plates secured to said endplate, said supporting plates being made of electrically nonconductive material; 12. In an apparatus for electrolytically shaping an electrically conductive and electrochemically erodable workpiece in a work area, the combination comprising, a drivehead assembly including an elongate ram cooperating with a stationary guide block and adapted to move axially back and forth, said ram having a first end within the work area on one side of said guide block, said first end of said ram having a hollow electrode and an electrolyte manifold chamber mounted thereon, said electrode communicating with said electrolyte manifold chamber, said ram including a shaft extending through a longitudinal hole in said guide block, means connecting said shaft to said manifold chamber, said connecting means including electrically nonconductive means whereby said shaft is electrically insulated from said electrode and electrolyte manifold chamber, a bus rod and an electrolyte tube extending through holes in said guide block, connected to said manifold chamber and being supported in spaced relationship with said guide block by electrically insulating bushings mounted in said guide block, high current capacity cable means to supply high amperage, direct current to said 'bus rod on an opposite side of said igHld block, electrolyte supply hose means to supply electrolyte connected to said electrolyte tube on said opposite side of said guide block, whereby the work area is free of electrolyte supply hoses and current supply cables, and drive means to move said ram operatively connected to said shaft on said opposite side of said guide block.

13. The apparatus of claim 12, wherein said bus rod and electrolyte tube are supported in spaced relationship from said guide block.

14. The apparatus of claim 12, wherein said electrolyte tube has a section thereof made of electrically nonconductive material.

15. The apparatus of claim 12, wherein said means to supply electrolyte includes a grounded sacrificial pipe section.

16. In an apparatus for electrolytically shaping an electrically conductive and electrochemically eroidable workpiece in a work area, the combination comprising, a drivehead assembly including an elongate stationary guide block, at least two ram elements guided by said guide block for movement axially back and forth, means forming an electrolyte manifold chamber and an electrode mount mounted on said ram elements at one end thereof, a shaping electrode carried on said electrode mount, projecting into the work area and communicating with said manifold chamber, a flexible boot enclosing said one end of said ram elements and having one end fixed relative to said guide block and its other end secured to said manifold forming means, an electrolyte tube movably extending through said guide block, projecting into said boot and connected to said manifold chamber, electrolyte supply hose connected to said tube at its end opposite said manifold for supplying electrolyte under pressure thereto, a bus bar movably extending through said guide block, projecting into said boot and electrically connected to said electrode, a plurality of high current capacity cables connected to said bus bar at its end opposite said electrode for supplying high amperage, direct current to said bus bar, whereby the work area is free of electrolyte supply hoses and current supply cables, and means connected to said ram elements at a second end thereof to move said elements back and .forth in said guide block.

17. An electrolytic machine including an electrolytic cavity sinking apparatus and a work holder assembly, said work holder assembly including a rotatably mounted spindle having a first end which extends into a work area, said first end having mounted thereon a work holder adapted to support a workpiece, a second end of said spindle being outside said work area, and means connecting said second end of said spindle with a source of positive potential, and said electrolytic cavity sinking apparatus includes a drivehead assembly having a ram cooperating with an elongate stationary guide block and adapted to move axially back and forth, said ram having a first end within said work area 'having a hollow electrode and an electrolyte manifold chamber mounted thereon, said electrode communicating with said electrolyte manifold chamber, said guide block having longitudinally extending holes therethrough, a shaft forming a part of said ram, bus rod, and electrolyte tube extending through said holes in said guide block, electrically nonconductive means con necting said shaft to said first end of said ram, drive means connected' to said shaft to move said first end of said ram forward and backward, said bus rod and electrolyte tube being connected to said electrolyte manifold chamber to supply a negative potential and electrolyte, respectively, to said electrode and said electrolyte manifold chamber, electrolyte supply hose connected to that end of said tube opposite said manifold chamber, and a plurality of high current capacity cables connected to that end of said bus rod opposite said electrode, whereby the .work area is free of electrolyte supply hoses and current supply cables.

18. The apparatus of claim 1, including a work holder assembly, said work holder assembly including a rotatably mounted spindle having a first end which extends into the work area, said first end having mounted thereon a work holder adapted to support a workpiece, a second end of said spindle being outside said work area, and brushes connecting said second end of said spindle with a source of positive potential.

References Cited by the Examiner UNITED STATES PATENTS 2,946,731 7/ 1960 Falls 204--143 3,056,734 10/ 1962 Scott 204-143 3,058,895 10/ 1962 Williams 204224 3,072,777 1/ 1963 McKechnie 219--69 3,092,710 6/ 1963 Kiriltsev et al 2196-9 I References Cited by the Applicant UNITED STATES PATENTS 2,826,540 3/ 1958 Keeleric. 2,905,605 9/ 1959 Keeleric. 2,920,026 1 1960 Kistler. 3,130,140 4/ 1964 Malkowski.

JOHN H. MACK, Primary Examiner.

ALLEN B. CURTIS, Examiner.

H. S. WILLIAMS, W. VAN SISE, Assistant Examiners. 

1. IN AN APPARATUS FOR ELECTROLYTICALLY SHAPING AN ELECTRICALLY CONDUCTIVE AND ELECTROCHEMICALLY ERODABLE WORKPIECE IN A WORK AREA, THE COMBINATION COMPRISING, A DRIVEHEAD ASSEMBLY INCLUDING A RAM AND AN ELONGATED HOLLOW SHAPING ELECTRODE MOUNTED ON ONE END THEREOF, SAID ELECTRODE EXTENDING INTO THE WORK AREA, SAID RAM BEING SUPPORTED AND GUIDED AT AXIALLY SPACED POSITIONS FOR AXIAL MOVEMENT THEREOF, MEANS CONNECTED TO THE SECOND END OF SAID RAM FOR MOVING SAID RAM TOWARD AND AWAY FROM THE WORKPIECE, SAID RAM INCLUDING MEANS AT SAID FIRST END THEREOF FORMING A HOLLOW MANIFOLD CHAMBER, MEANS INCLUDING CONDUIT MEANS EXTENDING THROUGH SAID RAM TO SUPPLY ELECTROLYTE UNDER PRESSURE TO SAID CHAMBER FROM SAID SECOND END OF SAID RAM, MEANS TO CONDUCT ELECTROLYTE UNDER PRESSURE FROM SAID CHAMBER TO THE WORK GAP BETWEEN SAID ELECTRODE AND THE WORKPIECE, AND MEANS INCLUDING BUS BAR MEANS EXTENDING THROUGH SAID RAM TO SUPPLY HIGH DENSITY, DIRECT CURRENT TO SAID ELECTRODE FROM SAID SECOND END OF SAID RAM, ELECTROLYTE SUPPLY HOSE CONNECTED TO SAID CONDUIT MEANS ADJACENT SAID SECOND END OF SAID RAM, AND A PLURALITY OF HIGH CURRENT CAPACITY CABLES CONNECTED TO SAID BUS BAR MEANS ADJACENT SAID SECOND END OF SAID RAM, WHEREBY THE WORK AREA IS FREE OF ELECTROLYTE SUPPLY HOSES AND CURRENT SUPPLY CABLES FOR SAID ELECTRODE. 